Convertible work-feeding devices for sewing machines



May 23, 1967 5, J KETTERER ET AL 3,320,912

CONVERTIBLE WORK-FEEDING DEVICES FOR SEWING MACHINES Filed Feb. 18, 1965 2 Sheets-Sheet l Fig; 3.

INVENTORS.

Sfonle J. Keiflerpr and BY Mun red R. Loldig W V ATTORNEY.

May 23, 1967 5 J, ETT ET AL 3,320,912

CONVERTIBLE WORK-FEEDING DEVICES FOR SEWING MACHINES Filed Feb. 18, 1965 2 SheetsShe et 2 32 ////////////////1 INYENTORS Stunle J. Kefferer and Mo rfred R. Ldidiq WlTNESS BY y JWM 77W KL,

TT'ORNEY United States Patent 3,320,912 CONVERTIBLE WORK-FEEDHNG DEVICES FOR SEWENS MAQHHNES Stanley J. Ketterer, Morris Plains, and Manfred It. Laidig,

Whippany, N..l., assignors to The Singer (Iompany,

New York, N.Y., a corporation of New Jersey Filed Feh. 18, 1965, der. No. 433,680 tlllaims. ((11. 112-210) This invention relates to work-feeding devices for sewing machines and more particularly to a convertible workfeeding device for a sewing machine which is capable of both straight-stitch and zigzag-stitch sewing.

In zigzaz sewing machines, it is highly desirable to include a provision for straight-stitch sewing in order to enchance the versatility of the machines. Particularly, in zigzaz machines purchased for household use, straightstitch sewing may constitute the sewing operation most frequently performed. For uniform feeding of the work in both straight-stitch and zigzag-stitch sewing, it is advantageous to feed the work by means of a feed dog which has at least two rows of teeth to grip the work on each side of the seam. Unfortunately, the optimum lateral distance between the rows of teeth is different for straight-stitch sewing and for zigzag-stitch sewing. In zigzag-stitch sewing, the rows of teeth have to be sufficiently far enough apart to provide clearance for the extreme penetrations of the sewing needle as it swings from side-to-side in its zigzag course. But, in straightstitch sewing, since the needle path is fixed it is possible for the seam-straddling rows of teeth to be more closely spaced for more uniform and wrinkle-free feeding of the work.

It is, therefore, a primary object of this invention to provide a convertible work-feeding device for a sewing machine.

Another object of the invention is to provide a convertible work-feeding device for a sewing machine, the work-feeding device being convertible to approach 0ptimum work-feeding conditions in both straight-stitch and zigzag-stitch sewing.

The main feature of the invention is the provision of means to adjust the lateral spacing between seam-straddling rows of teeth in a work-feeding device for a sewing machine. In zigzag-stitch sewing, the teeth are placed in sufficient open position to furnish clearance for the zigzag needle penetrations while in straight-stitch sewing, the teeth are placed in close position for uniform and wrinkle-free work feeding. The means for adjusting the lateral distance between the teeth include an elongated auxiliary feed bar carrying one of the rows of teeth which in effect constitute an auxiliary feed dog, while the other teeth constitute a main feed dog. An auxiliary feed bar is pivotally mounted on a concentric portion of an eccentric stud rotation of which permits adjustment of the height of the teeth of the auxiliary feed dog relatively to the height of the teeth of the main feed dog. The length of the elongated auxiliary feed bar between the pivot stud and the top of the auxiliary feed dog and the small lateral displacement involved makes the slight tilt of the auxiliary feed dog minimal when in either open or close position.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings in which:

FIG. 1 is a top plan view of a work-supporting bed of a sewing machine incorporating a work-feeding device of the invention with the teeth in open position for zigzagstitch sewing;

FIG. 2 is a cross sectional view of the work-supporting bed of FIG. 1 taken normal to the line of Work feed;

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FIG. 3 is a cross sectional view of the work-supporting bed taken parallel to the line of work feed;

FIG. 4 is a top view of the work-supporting bed of FIG. 1 with the teeth of the work-feeding device in close position for straight-stitch sewing;

FIG. 5 is a cross sectional view of the work-supporting bed as shown in FIG. 4, taken normal to the line of work feed; and

FIG. 6 is an exploded perspective view of the workfeeding device of the invention.

With reference to the drawings, the work-feeding device of the invention is illustrated as incorporated in a conventional sewing machine having a frame which includes a work-supporting bed 10 and a sewing head 11. Mounted in the sewing head is an endwise-reciprocating needle bar 12 to which is clamped by means of a clamping screw 13 a thread-carrying needle 14. The thread-carrying needle is adapted to cooperate with a complementary stitch-forming mechanism represented by a loop taker 15 mounted inside the work-supporting bed. Also mounted in the sewing head 11 is a presser bar 16 the relevance of which will be explained later.

Inside the work-supporting bed 10 is a work-feeding mechanism of the type commonly referred to as a fourmotion drop feed work-feeding mechanism. The workfeeding mechanism includes a feed-advance rock shaft 17 mounted between two pintles 18 of which only one is shown. Pivotally supported between a pair of rock arms 19 upstanding from the feed-advance rock shaft 17 is a feed bar 20 to which the rock arms impart feed advance and return motion in response to oscillation of the rock shaft 17.

With particular reference to FIG. 6, the feed bar 20 has a depending portion 21 at its distal end and by means of screws 22 mounts two rows of feed teeth 23 and 24 which in effect constitute a main feed dog 25. Therefore, hereinafter, the feed bar 20 will be referred to as the main feed bar.

At the bottom of the depending portion 21 of the main feed bar 20, there is an auxiliary feed bar mounting means or bracket 26 which may be connected to the depending portion 21 as by brazing 27. To the auxiliary feed bar mounting bracket 26, there is pivotally connected an elongated auxiliary feed bar 28. The pivotal means for mounting the auxiliary feed bar 28 includes a pivot stud 29 which has a concentric portion 30. A setscrew 31 in the bracket 26 and bearing against an eccentric portion 32 of the pivot stud 29 maintains the eccentric portion 32 of the stud against rotation and in a preset orientation whereby to provide for adjustment of the height of the auxiliary feed bar 28. At the top of the elongated auxiliary feed bar 28, there is a row of feed teeth 33 which in effect constitute an auxiliary feed dog 34. A stop means or bracket 35 secured to the front of the depending portion 21 of the main feed bar 20 by means of screws 36 limits the extent of swinging lateral movement of the auxiiliary feed dog 34.

Pivotally connected to the depending portion 21 of the main feed bar 20 by means of a pivot screw 38 is a feed-1ift connecting lever 39 which serves to impart feed-lift motion to the main feed bar 20 in synchronism with the feed advance and return motion imparted by the feedadvance rock shaft 17. Since the convertible work-feeding device of this invention may be used with any conventional driving means for the feed-advance and feed-lift mechanism, only the feed-advance rock shaft 17 and the feed-lift connecting lever 39 are disclosed. herein.

In operation, when it is desired to perform zigzagstitch sewing, the teeth 23, 24 and 33 of the feed dogs 25 and 34 are placed in open position as shown in FIGS. 1 and 2 to provide clearance for the zigzag movements of the reciprocating needle 14 which penetrates between the endmost rows of feed teeth 23 and 33. The teeth of the feed dogs rise above correspondingly positioned slots 40 in a throat plate 41 to cooperate with a soleplate 42 of a presser device or foot 43 to feed work to be sewn which is placed on the work-supporting bed 10. The throat plate 41 is removably mounted on the worksupporting bed by means of two downwardly springbiased posts 44, while the presser foot 43 is removably clamped to the presser bar 16' by means of a clamping screw 45. Both the throat plate 41 and the presser foot 43 contain laterally elongated needle-clearance slots or apertures 46 and 47 respectively, to accommodate the lateral penetrations of the needle.

When it is desired to switch to straight-stitch sewing, the throat plate 41 is removed from the work-supporting bed 10 and, as shown in FIGS. 4 and 5, the teeth 23, 24,

and 33 of the feed dogs 25 and 34 are placed in close position by the application of slight finger pressure to the teeth 33 of the auxiliary feed dog 34. The close position of the teeth of the feed dogs for straight-stitch sewing provides uniform and Wrinkle-free work feeding which is not possible to obtain with known zigzag machines, the work-feeding mechanisms of which are not convertible and by necessity must have the feed teeth spaced far apart to provide clearance for zigzag needle penetrations.

In the present invention, with the teeth of the feed dogs in close position for straight-stitch sewing, a second throat plate 48 having slots 49 corresponding to the teeth of the feed dogs in close position is substituted for the throat plate 41 because the slots 40 of the throat plate 41 no longer line up with the teeth of the feed dogs. In addition, the presser foot 43 may be replaced in favor of a presser foot t) having a narrower sole-plate 51 corresponding to the teeth of the feed dogs in close position.

The stop bracket 35 limits the maximum open and minimum close positions of the auxiliary feed dog 34. However, it is the slots 40 or 4-9 in the throat plate 41 or 48 which maintain the feed teeth 23, 24 and 33 in open or close position depending on which throat plate 41 or 48 is secured to the work-supporting bed of the sewing machine. Since the feed-lift movement imparted to the feed bar by the conventional feed-lift mechanism is such that the teeth of the feed dogs and 34 never drop below the bottom 52 or 53 of the throat plate, the throat plate slots or 49 will act as guides for the rows of feed dog teeth to maintain the selected spacing therebetween. The eccentric portion 32 of the pivot stud 38 permits adjustment of the height of the teeth of the auxiliary feed dog relative to the height of the teeth of the main feed dog while the length of the elongated auxiliary feed bar 28 from the pivot stud 29 to the top of the auxiliary feed dog 34 and the slight lateral displacement involved maintains the top of the teeth 33 of the auxiliary fed dog 34 substantially in a plane coincident with a plane determined by the top of the teeth 23 and 24 of the main feed dog 25 whether the auxiliary feed dog 34 is in open position for zigzag-stitch sew-ing or in close position for straight-stitch sewing.

Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form-has been made by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention.

Having thus set forth the nature of the invention, what is claimed herein is:

1. A convertible work-feeding device for a sewing machine having a frame including a work-supporting bed and a sewing head, a thread-carrying needle mounted in the sewing head for endwise reciprocation wit-h respect to the work-supporting bed, stitchforming mechanism complemental to said thread-carrying needle mounted in the work-supporting bed, and a work-feeding actuating mechanism mounted on said frame and connected to said convertible work-feeding device, said convertible work-feeding device comprising a pair of workgripping means having work-gripping surfaces located substantially laterally opposite and substantially parallel to each other, and means for adjusting the lateral distance between the work-gripping surfaces of said workgripping means.

2. A convertible work-feeding device for a sewing machine having a frame including a work-supporting bed and a sewing head, a thread-carrying needle mounted in the sewing head for endwise reciprocation with respect to the work-supporting bed, stitch-forming mechanism complemental to said thread-carrying needle mounted in the work-supporting bed, and a work-feeding actuating mechanism for said convertible work-feeding device mounted in the work-supporting bed, said convertible work-feeding device comprising a main feed bar connected to the workfeeding mechanism in the work-supporting bed, a main fed dog having at least one row of teeth and mounted on the main feed bar, an auxiliary feed bar operatively connected to the work-feeding mechanism, an auxiliary feed dog having at least one row of teeth and mounted on the auxiliary feed bar with the teeth disposed substantially laterally opposite and substantially parallel to the teeth of the main feed dog, and means for adjusting the lateral distance between the rows of teeth of the feed dogs.

3. A convertible work-feeding device for a sewing machine which is capable of both straight-stitch and zigzagstitch sewing and has a frame including a work-supporting bed and a sewing head, a thread-carrying needle mounted in the sewing head for endwise reciprocation with respect to the work-supporting bed, stitch-forming mechanism complemental to said thread-carrying needle mounted in the work-supporting bed, and a work-feeding mechanism mounted in the work-supporting bed, said convertible work-feeding device comprising a main feed bar connected to the work-feeding mechanism in the work-supporting bed, a main feed dog having at least one row of teeth and mounted on the main feed bar, an auxiliary feed bar operatively connected to the workfeeding mechanism, an auxiliary feed dog having at least one row of teeth and mounted on the auxiliary feed bar with the teeth disposed substantially laterally opposite and substantially parallel to the teeth of the main feed dog, and means for adjusting the lateral distance between the rows of teeth of the feed dogs from close position for straight-stitch sewing to sufficiently open position to provide clearance for needle penetrations in zigzag-stitch sewing.

4. A convertible work-feeding device for a sewing machine having a frame including a sewing head and a work-supporting bed which has means for mounting removable throat plates, a thread-carrying needle mounted in the sewing head for endwise reciprocation with respect to the work-supporting bed, stitch-forming mechanism complemental to said thread-carrying needle mounted in the work-supporting bed, and a work-feeding mechanism mounted in the work-supporting bed to which said convertible work-feeding device is connected, said convertible work-feeding device comprising a main feed bar connected to the work-feeding mechanism in the work-supporting bed, a main feed dog having at least one row of teeth and mounted on the main feed bar, an auxiliary feed bar operatively connected to the work-feeding mechanism, an auxiliary feed dog having at least one row of teeth and mounted on the auxiliary feed bar with the teeth disposed substantially opposite and substantially parallel to the teeth of the main feed dog, means for selectively adjusting the lateral distance between the rows of teeth on the feed dogs, and at least two throat plates adapted to be selectively and removably mounted on said work-supporting bed by said mounting means and having at least two parallel feed slots with difierent lateral spacing, said feed slots adapted to maintain the selected lateral distance between the rows of teeth on the feed dogs.

5. A convertible work feeding device for a sewing ma chine which is capable of both straight-stitch and zigzagstitch sewing and has a frame including a work-supporting bed and a sewing head, a thread-carrying needle mounted in the sewing head for endwise reciprocation with respect to the work-supporting bed, stitch-forming mechanism complemental to said thread-carrying needle and mounted in the work-supporting bed in opposition to the threadcarrying needle, and a four-motion drop feed work-feeding mechanism mounted in the work-supporting bed, said convertible work-feeding device comprising a main feed bar connected to the four-motion drop feed work-feeding mechanism in the work-supporting bed, a main feed dog having at least one row of teeth and mounted on the main feed bar, an auxiliary feed bar operatively connected to the four-motion drop feed work-feeding mechanism, an auxiliary feed dog having at least one row of teeth and mounted on the auxiliary feed bar with the teeth disposed substantially laterally opposite and substantially parallel to the teeth of the main feed dog, and means for adjusting the lateral distance between the rows of teeth of the feed dogs from close position for straight-stitch sewing to sufficiently open position to provide clearance for needle penetrations in zigzag-stitch sewing.

6. A convertible work-feeding device for a sewing ma chine which is capable of both straight-stitch and zigzagstitch sewing and has a frame including a work-supporting bed and a sewing head, a thread-carrying needle mounted in the sewing head for endwise reciprocation with respect to the work-supporting bed, stitch-forming mechanism complemental to said thread-carrying needle mounted in the work-supporting bed, and a work-feeding mechanism mounted in the work-supporting bed, said convertible Work-feeding device comprising a main feed bar connected to the work-feeding mechanism in the work-supporting bed and having a depending portion at the distal end, a main feed dog having at least one row of teeth and mounted on the main feed bar, an auxiliary feed bar mounting means at the bottom of the depending portion of the main feed bar, an elongated auxiliary feed bar pivotally connected to the auxiliary feed bar mounting means by pivotal means so that the remote distal end can move laterally relative to the teeth of the main feed dog, and an auxiliary feed dog having at least one row of teeth and mounted on the distal end of the auxiliary feed bar with the teeth disposed substantially laterally opposite and substantially parallel to the teeth of the main feed dog, said 6 rows of teeth of said feed dogs adapted to be laterally adjusted from close position for straight-stitch sewing to sutficiently open position to provide clearance for needle penetrations in Zigzag-stitch sewing.

7. The convertible work-feeding device of claim 6 in which said pivotal means by which said auxiliary feed bar is pivotally connected to said auxiliary feed bar mounting means includes an eccentric portion which may be rotationally adjusted to adjust the height of the teeth of said auxiliary feed dog relatively to the teeth of said main feed dog.

8. The convertible work-feeding device of claim 6 which includes stop means for limiting the minimum close posi tion and the maximum open position of said feed dogs.

9. The convertible work-feeding device of claim 6 which includes a pair of throat plates adapted to be selectively and removably secured to said work-supporting bed, one of said throat plates having feed dog slots corresponding to said rows of teeth of said feed dogs in close position for straight-stitch sewing and the other of said throat plates having feed dog slots corresponding to said rows of teeth of said feed dogs in open position for zigzagstitch sewing and a laterally elongated needle aperture to provide clearance for needle penetrations in zigzag-stitch sewing.

10. The convertible work-feeding device of claim 9 which includes a pair of presser devices adapted to be selectively and removably secured to a presser bar mounted in said sewing head in opposition to a selected one of said throat plates, one of said presser devices adapted for straight-stitch sewing and having a narrow sole-plate to oppose said rows of teeth of said feed dogs in close position and the other of said presser devices adapted for zigzag-stitch sewing and having a wider sole-plate to oppose said rows of teeth of said feed dogs in open position and a laterally elongated needle slot to provide clearance for needle penetrations in zigzag-stitch sewing.

References Cited by the Examiner UNITED STATES PATENTS 1,139,051 5/1915 Mofiatt ll22l0 3,025,812 3/1962 Engel 112-168 X JORDAN FRANKLIN, Primary Examiner. H. H. HUNTER, Assistant Examiner. 

1. A CONVERTIBLE WORK-FEEDING DEVICE FOR A SEWING MACHINE HAVING A FRAME INCLUDING A WORK-SUPPORT BED AND A SEWING HEAD, A THREAD-CARRYING NEEDLE MOUNTED IN THE SEWING HEAD FOR ENDWISE RECIPROCATION WITH RESPECT TO THE WORK-SUPPORTING BED, STITCH-FORMING MECHANISM COMPLEMENTAL TO SAID THREAD-CARRYING NEEDLE MOUNTED IN THE WORK-SUPPORTING BED, AND A WORK-FEEDING ACTUATING MECHANISM MOUNTED ON SAID FRAME AND CONNECTED TO SAID CONVERTIBLE WORK-FEEDING DEVICE, SAID CONVERTIBLE WORK-FEEDING DEVICE COMPRISING A PAIR OF WORKGRIPPING MEANS HAVING WORK-GRIPPING SURFACES LOCATED SUBSTANTIALLY LATERALLY OPPOSITE AND SUBSTANTIALLY PARALLEL TO EACH OTHER, AND MEANS FOR ADJUSTING THE LATERAL DISTANCE BETWEEN THE WORK-GRIPPING SURFACES OF SAID WORKGRIPPING MEANS. 